Transmission



R. CHILTON TRANSMISSION April 9, 1946.

Filed March 29, 1943 l 4 Sheets-Sheet l a. Il.

M T R ma w. NH R EC o mn n l A m. Y R B April 9, 1946. R. CHILTON TRANSMISSION Fileduarch 29, 1943 K 4 Sheets-Sheet 2 April 9, 1946.

R. CHILTON TRANSMISSION Filed March 29, 1943 4 Sheets-Sheet 3 |NvEN-ron ROLAND GEIL TON.

mw ArroRNEY April 9, 1946. R CHlLTON 2,398,208

TRANSMISSION Filed March 29, 1943 4 SheebS--Sheell 4 INVENTOR RoLANn CHILTUN.

ATTORNEY Patented'Apn 9, 1946 UNITED STATES PATENT OFFICE TRANSMISSIQN Roland Chilton, Ridgewood,vN. J., assignor to. Wright Aeronautical Corporation,A a corporation of New York Y Application March 29, 1943, serial No. 481,033

26 Claims.

This invention comprises" improvements in multi-speed transmissions for all purposes, the design represented by the drawings being for a tank transmission embodying seven speeds, and it is a feature of the invention that it is adaptable to any number of speeds with only minor changes in' the internal arrangement and length.

A prime object of the invention is to provide for extremely fast shifting from one gear to the next to overcomeonel of the diiiiculties found in I tanks and in heavy automotive equipment using conventional synchro-mesh shift" as follows:

' 4These devices absorb a definite time interval to produce synchronization which prevents rapid shifting and causes a relatively long power-off interval, which is particularly objectionable between the lower gears. 'Thus it will happen that a vehicle capable of .negotiating a. hill or heavy .terrain in second gear must be kept in rst gear because the heavy vehicle acquires little momen tum in rst gear and stalls in the power-oil.' shift interval before second gear can be engaged. This quick-shiftingv objective of this invention is inl part obtained by a novel dual clutch organization' later to be described. The special provisionsare designed with the intention of providing such rapidshifting and such clutch performance that the shift will be so rapid as to be made at full throttle, that is, without relaxing the accelerator pedal as usual in a conventional transmission. It is contemplated that a full-throttle shift will not result in excessive 'engine speed in virtue of Fig. 4 is an "axial section on the line 4-4 of Fig. 3;

Figs. 5 and 6' are end sections of an oil control valve incorporated in the cam; and

Fig. 'l is a fragmentary section showing an acceleration limiting device.

Referring rst to Fig. l, I0 represents'the input shaft of the transmission which may be the crankshaft of an associated engine. The shaft I Il is equipped with splines' I2 on which is slidable an inner clutch member I 4'provided also with external splines I8 onV which are mounted clutch plates I6 of a multiple disc clutch. Intermediate the clutch plates I6 are outer clutch platesl having external splines engaged with splines 22 formed in an outer drum 24 having an end-plate 26 which also comprises a hydraulic cylinder for a `clutch applying piston 28. vThe platel 2B has an extension 30 equipped with a thrust flange 32 and engaging a. shift collar 34 having trunnions 38 (seev also Fig. 2) engaged by shifting arms 38 cooperating'with shift mechanism later 'to be described.

Surrounding and concentric with the clutch mechanism just described are aseries of gears I, 2, 3, 4. 5 and 6, and a direct drive gear 1. All

I of these gears have bores of the same diameter as indicated by B for gears numbered 6 and 1.

At the righthand end of the clutch drum 24, there is a circumferential clutching land or sury face 40 which, as fabricated, has an outside diamthe extreme rapidity of shift. 4As will be obvious from the 4later description, one clutch element may be regarded as a synchro-mesh device but, in this case, it is one having capacity to transmit the entire engine torque as compared to the small fraction thereof which is withimthe capabilities` of the conventional synchronizing means.

y Another object of the inventionv is to provide a transmission of many speeds wherein the gearing subtends a minimum length, thus simplifying the construction, reducing the weight and bulk,

eter which is aelose running iit so as to be slidable through the bores of the gears from one to another. Beneath this clutching land the drum 24 has arconical inner surfac`42 and a corresponding cone is formed on the circumference 5 y of a heavy reaction plate 44; balls 46 being interand eliminating the necessity for intermediate posed so that should the reaction or'wedge member 44 be pressed to the right, the balls 46 comprise an anti-friction means exerting a relatively great bursting pressure on the drum 24 beneath the clutching land 40. It will be seen that should hydraulic pressure be admitted to the piston 28 I this will engage the clutch plates I6 and 20 while the piston. pressure reacts also on the reaction plate 44. The clutch drum 24 and its element 40 are relatively thin; so much so, in fact, that they might be overstressed if full hydraulic pressure should be applied to the assembly when the land 40 is not restrained by one of the gear bores to be engaged. Assuming,'for example. that the land 48 was 8 inches in diameter, then at 60,000 pounds stress (for steel) the clutching land would expand 16hmm". 'I'he clearance of the land'40 in its relaxed positionfrom the bores B will be only a small fraction of this elastic expansive capacity stantial expansion.

the clutch drum 24 may be axiallyA slotted at the clutch land 40 as in conventional expanding collets. While the clutch ring element 4I is so thin as to be unable of itself to resist the bursting force from the balls 4I, yet it will be seen that each of the engaged gears I, I, I, 4, I, I, and l is a relatively massive member able to resist sub- 'I'he multiple clutch plates II and II have a relatively great agmste surface suited for durability under substantial slipping. 'I'he angle of the coned surfaces engaged by the expanding balls 4I, and the number and relative diameter of the clutch plates is so proportioned that the torque capacity of the expanding clutch 4I is substantially in excess of that of -the slippable clutch plates II and II. However, both elements are subject to a com'mon primary actuating force, i. e., the oil pressure on the piston II, so that it should be obvious that, when such pressure is applied, the expanding clutch element 4I will clutch the appropriate gear with suilicient power to cause the slippage to occur almost exclusively at the clutch plates. Actually, the small amoimt of slippage at the expanding clutch will depend on the inertia of the drum I4. II and the associated clutch plates II, and it is a feature of this invention that these parts possess very little inertia compared to conventional automotive clutches usually comprising a single plate necessarily requiring relatively great diameter and flywheel effect. It is intended that the slippage of the circumferential clutch surface 4I when the selected gear is engaged, will for this reason only be a small fraction of a revohxtion leaving the plate clutch to take the many revolutions of slip necessary for a gear shift. This result is achieved by having the expanding clutch of predominating torque capacity and light weight. It will be seen that this clutch has only to accelerate the elements 24, 2I and 2I whereas the large surface multiple plate clutch has to accelerate the entire vehicle or decelerate the entire engine, as the case may be.

As described the clutch 4I can transmit `considerably more torque without slipping than the multiple plate clutch II, II. In addition, as compared to the clutch 4I, the plateclutch II, II is capable of withstanding considerably more slipping without damage to the clutch. Accordingly, the clutch 4I may be described as having a relatively large torque capacity and the plate clutch II, II as having relatively large slippagecapacity.

In conventional gear shift transmissions, multiple plate clutches such as the clutch I I, 20 have, in general, been abandoned in favor of single plate clutches because `the multiple arrangement, although much lighter and more compact, gives diiiiculties due to residual drag in the disengaged position, which interferes with silent gear shift-- ing. This limitation, however, is of n0 moment in the present invention where the actual engagement and disengagement is affected by the expansion and contraction of the smooth circular clutch element 4I, which is in series with the multiple plate clutch wherein very slight contraction `will completely disengage the clutch assembly from the gears for free shifting, as later to be described.

Burroimding the gears I, 2, I, 4, l, I, and 'I are a plurality of layshafts 4I supported in suitable aseaaoe bearings III and II and rigidly carrying a plurality of various diameter layshaft gears IL, IL, IL, 4L, IL, and IL, constantly meshed with the respective gears I, 2, I, 4,l l and I to drive each at correspondingly varying speed ratios. The layshafts 4I have, at their right hand ends, pinions I4 meshed with an internal gear II and an external gear II, these gears comprising driven members of the transmission; the gear II giving forward speeds and the gear II reverse speeds of slightly greater reduction ratio. The forward and reverse drives are selected by a toothed clutch II slidable by means of a shift collar I2 and lever I4 operated by the hand lever II. By this means the toothed clutch II can be selectively engaged with companion teeth II and 1I in the gears II and II respectively. The nnal drive or output shaft of the transmission 1I is equipped at its inner end with splines 'I4 engaging companion splines out beneath the splines II in the reverse selector member 1I. s l

The shifting functions operate as follows: First, referring to Figs. 2 and 3, where it is seen that the shifting arms II which, as previously described, engage the trunnions II in the shift collar I4, are telescoped within respective arms 1I comprising, with the hub II, a forked shiftlever actuated by a rock-sluit Il. One or both of the arms II is provided with an oil duct I4 communicating with the inside of the hollow shaft I2 and through the hollow trunnions II to an annulus II in the shift collar I4. Suitable holes and slots indicated at II, 1"ig.,1, convey the actuating 'oil pressure to the piston II which actuates the compound clutch. At its right hand end. the rock-shaft I2 is engaged by an oil conveying stub II which, in turn, communicates with a duct I2, Fig. 2. The other end of this duct is seen at I2 in Fig. 4 as communicating with the interior of a hollow shifting cam I4 seen also in outside view in Fig. 3. This cam is engaged by a stud II at the end of a lever II seen in full view in Fig. 3 and rigid with the righthand end of the rock-shaft I2, Fig. 2 (where only the hub of the lever II is seen). In other words, the shift-cam engaging lever II and the shift collar arms II swing rigidly with the rockshaft I2.

At its upper end the cam I4 has a pinion III engaged by a gear quadrant III (Figs. 2 and I) integral with a primary control shaft II4. This operating shaft III may be rocked by means of a conventional manual gear shift lever (not shown) or by any suitable automatic gear shift means. It will be seen that the cam I4, Fig. 3, consists of parallel elements III and inclined elements III so that while the cam moves through the arcs subtended by the parallel elements, the shift lever II, and therefore the entire clutch assembly, is locked from axial motion. 'Diese- (not shown) is at all times applied to a duct III which cooperates with valve holes III formed in the Journal of the cam I4 as seen in detail end section of Fig. 5. In the position shown, it may be observed that the interior of the cam is connected to pump-pressure which will devolve upon the clutch actuating piston II through the passages already described. To insure instantaneous :,seaaos and complete .relief of clutch actuating pressure when the pressure hole ||2 is closed by rotation of the cam, a second set of relief or dump holes are provided along 4the line 0-0, Fig. 4, as seen in section in Fig. 6, which relief holes ||0 are adapted to cooperate with the drain passage ||1.

As disclosed, the cam 94 has the dwell ele- 'ments |06 arranged at 90 intervals with the inclined elements |08 in between wherefore the cam will make one and/one-half revolutions in moving from gear I to gear 'I (direct drive) The "pressure control and dump valve holes 4 and It will ||8 are also arranged at 90 spacings. now be seen that with the cam in the position shown, i. e., with the stub 96 of the lever 90 on the parallel or dwell portion of the cam, initial movement of the quadrant |02 will rotate the camwithout moving the lever 00. Ifhis rotation cuts off the oil pressure to the clutches before the sloped element. |08 of the cam starts to shift the clutch assembly axially towards the next gear. For the same reason, this shift movement ceases when the next dwell cam element is reached and the subsequent movement of the cam holds theV lever 98 still while oil pressure is re-established by the valve holes ||4. Recapitulating, the sequence on moving the primary control shaft |04 and quadrant |02 from any gear position to the next is: First the clutch oilpressure is shut oiI. Then the clutch assembly is shifted axially into alignment with the next gear and then the clutch oil pressure is re-established on the piston 20. It is intended in practice that this sequence, which first unloads the` expanding clutch and the plateclutch I6, 20then moves the assembly to the adjacent gear and then re'- expands the clutch 40 and loads the clutch I6, 20,

can be performed with extreme rapidity since the shift is not delayed by synchronizing devices which conventionally prevent the completion of the shift motion until synchronization has occurred. In fact, it is intended that the interval between the disengagement of the expandingclutch 40 from one gear Iand its engagement to zero slip with the next gear will take place as' fast as it will be possible for an operator to move a control lever. However, it must be remembered that after the expanding clutch 40 has gripped the engaged gear to zero slip, slippage will then continue at the plate clutch I0, 20 'for whateverl Awith a prime objective of the invention.

The specific contact pressures of the expanding` clutch 40 are very high in order to minimize the slippage at this point Whereas the specific pressures at the main clutch plates themselves will be relatively low, in accordance with good practice for clutches which must sustain substantial slip.

'This pressure intensity ratio between the two rates of acceleration of ls. driven shaft would otherwise occur. For this purpose one of the layshaft gears suchvas .4L is engaged by a hollow Y gear I I8 which, accordingly, always runs at speed proportional to the driven shaft 12. Within the gear I 0 is a fiywheel or inertia member I 20 having a shaft |22 loaded to the right by an adjustable spring |24. A- circumferential plurality of opposed conical pockets |20 are formed in the hollow gear ||0 and in the ilywheel member |20 and engaged between these pockets are balls |28 which are, accordingly, subject to the axial pressure of the spring |24 and normally drive the inertia member |20 as a unit with the gear III. However, should an excessive acceleration or deceleration of the driven shaft 12 (and therefore the gear I0) impend, the inertia member |20 will lag. causing rotation relative to the gear ||8 and generating leftward axial movement of the mass |20 which is limited by a stop ring' |20. At its mid-length the shaft |22 is provided with a valving neck |02 which upon leftward axialvmovek ment uncovers a pressure escape hole |04 thereby connecting the clutch oil pressure via passagel be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I

40 aim in the appended claims to cover all such modicationsand changes.

I claim as my invention: l. In a transmission, a drive shaft, several gears concentric therewith affording several speeds, said gears having identical clutching bores defining an axially laminate composite cylinder, a. compound clutch" assemblage slidable as a unit along said shaft, said compoundclutch assemblage including a multiple plate clutch element, an element expansible into driving engagement selectively with the walls of anyone of said gear bores, and a. common means for loading both said clutch elements. k

2. In a transmission, a shaft, a compound clutch assemblage slidable asa unit to dierent gear stations therealong and comprising a multiple plate clutch element and a circumferentially expansible friction clutch element arranged in series, a common loading means for said clutch elements, said expanding clutch means having greater clutching torque capacity than said multiple plate clutch means, and a series of gears Yof different speeds having bores, the wallsl of which are selectively clutchable by said expanding element. g

3. In a transmission, a drive shaft, a compound clutching vunit slidable thereon and comprising a clutches in the example shown will be of the order of 30/1 and it'will be noted that this ratio obtains regardless of the 4actual load developed at any instant by the hydraulic clutch actuating piston 20.

Referring now to Fig. '7, a clutch pressure regv ulating device is shown which reduces the'y hl'-y draulic pressure on the clutch whenexcessive cylindrical .,expansible clutching element and a multiple plate -clutch element arranged in series and an hydraulic piston adapted to load both said elements, a plurality of gears selectively engageable by said expanding clutch element, and

gear shift actuating means comprising a cam invcluding hydraulic valving means and organized that-rotation of said cam from one gear shift position to the next ilrst shuts oi! hydraulic pressure, then moves the clutch assemblage to tbe next gear position and then restores said hydraulic pressure.

4. In a transmission, a shift-cam having anguiar shift-producing segments interspaced with dwell segments producing no shift motion, a

clutch shiftable by said cam and having hy" draulic clutch loading means, and hydraulic pressure valving means operatively associated with said cam so as to cut ci! operating pressure from said clutch before shifting the same and to restore said pressure after a shift movement has been completed.

5. In a transmission having several gear stations, a shift-cam including inclined segments interspaced with dweil segments, a hydraulically operable clutch, means for shifting said clutch from said cam, said cam including valving holes adapted when said cam is moved from one dwell segment to the next to first cut oiI hydraulic pressure from said clutch and then shift said clutch to an adjacent gear station and then restore hydraulic pressure, and a plurality of gears selectively engageable by said clutch at respective stations.

6. In a transmission, in combination, concentric gears affording different speeds arranged side-by-side with bores in said gears collectively comprising a composite cylinder, a clutch means shiftable along said cylinder and having an element expansible to selectively engage the several gears, a multiple plate clutch means in series with said expansible clutch element, an hydraulic piston adapted to load and unload both said clutch elements, and shift means including a cam and hydraulic pressure control means adapted to cut oi! said pressure, shift said clutch to an adjacent gear, and then restore the hydraulic pressure in the sequence stated.

1. A composite clutch unit for use in connection with a drive means comprising clutch plates, a piston hydraulically actuatable to eect engagement of said clutch plates, an annular clutch element serially connected with said clutch plates, and means operative upon the application oi' fluid pressure to said piston to radially strain said annular clutch member whereby said anannular member is adapted to frictionally engage said drive means.

8. A composite clutch unit for use in connection with a drive means comprising a pair of inner and outer concentric members, clutch plates disposed between said members, a piston actuatable in response to the application of fluid pressure thereto to effect engagement oi' said plates to provide a driving connection between said members, and means operative in response to said fluid pressure to effect radial extension or contraction of one of said concentric members, whereby said one concentric member is adapte te'frictionally engage said drive means.

9. A composite clutch unit comprising a ilrst member, a second member concentric therewith..

clutch plates disposed between said members, a piston hydraulically actuatable to engage said clutch plates to provide a driving connection between said members, a third member, generally parallel cones on the adjacent surfaces of said third -member and said iirst member, and a plurality` of balls disposed between said cones.

l0. A composite clutch unit comprising an inner and an outer concentric member, a multiplate clutch disposed between said members, a

piston hydraulically actuatable to engage said clutch plates to provide a driving connection between said members,A a reaction member, generally parallel cones on adjacent surfaces of said reaction member and one of said concentric members, and a plurality of balls disposed between said cones, said conical surfaces being so disposed that upon application of hydraulic pressure to engage said clutch plates said reaction plate is movable to wedge said balls between said cones.

11. A composite clutch unit for use in connection with a drive means comprising a first member. a second member concentric therewith, clutch plates disposed between said members, a

piston movable in response to the application of iluid pressure thereto to engage said clutch plates to provide a driving connection between said members, a third memberl disposed between said ,4

concentric members and movable in response to the application of iluid pressure, and means disposed btween said third member and said nrst member and adapted upon application of fluid pressure to radially strain said first member to engage said drive means.

l2. In a transmission, a multi-speed gearset, a clutch means of relatively large friction torque capacity, control means adapted to shift said clutch means relative to said gearset for selective frictional engagement therewith, and a second clutch means of relatively large slippage capacity serially connected in said transmission, said two clutch means forming an assembly slidable as a unit.

13. In a multi-speed transmission, a drive member, a plurality of gears disposed in side by side relation and having a bore extending therethrough coaxially with said member, a clutch slidable along said member within said bore and having an annular element radially expansible by hydraulic pressure into engagement with a selected gear, and a composite cam and Ifluid pressure control operable to sequentially cut oi! said hydraulic pressure, shift said clutch, and e restore said hydraulic pressure.

14A. In a multi-speed transmission, a plurality of coaxial gears disposed in side by side relation.

a compound clutch unit axially slidable relative to said gears and comprising a clutch having a relativelyl large .slippage capacity serially connected with an annular clutch member having a relatively large clutching torque capacity, common means for loading said large slippage c apacity clutch and for circumferentially stressing said annularclutch member into frictional engagement with a selected gear, and means for selectively shifting` said compound clutch unit relative to said gears.

l5. In a multi-speed transmission, a plurality of coaxial gears disposed in side by side relation, a compound clutch unit axially slidable relative to said gears, said compound clutch unit comprising clutch plates of relatively large slippage capacity serially connected with an annular clutch member having a relatively large clutching torque capacity, nuid pressure means for loading saidclutch plates and for circumferentially stressing said annular `clutch member into frictional engagement with a selected gear, means for selectively shifting said compound clutch unit relative ing a bore extending therethrough, said gears being drivably connected to one of said members, the other of said members being coaxial with said gears and extending into said bore in clearance relation thereto, a compound clutch unit slidably splined to said other member and extending into said bore, and means for selectively shifting said compound clutch unit relative to said gears, said compound clutch unit comprising a clutch having relatively large slippage capacity and a serially connected annular clutch element of relatively large clutching torque capacity radially extendible into frictional engagement with a selected Sear.

17. In a multi-speed transmission, a driving member, a driven member, a plurality of coaxial gears disposed in side by' side relation and having a bore extending therethrough, said gears being drivably connected to one of said members, the

other of said members being coaxial with said gears and extending into said bore in clearance relation thereto, an axially slidable compound clutch unit .extending into said bore, and means for selectively shifting said clutch unit relative to said gears, said clutch unit comprising an inner member slidably spiined to said other member, an outer member concentric with said inner member, clutch plates disposed between said concentric members, 'a piston hydraulically actuatable to engage said plates and provide a driving connection between said concentric members, and reaction means operable upon application of iluid pressure to said piston to radially extend the adjacent portion of said outer concentric inembers into frictional engagement with a selected gear. v

18. In a transmission, a plurality of gears providing diiferent speed drive ratios, clutch means of relatively large friction torque capacity selec.- tively shiftable relative to said gears for frictional engagement with a selected gear, a second clutch means of relatively large slippage capacity serialv 1yv connected in said transmission, and a unitary control member operable to ilrst effect disengagement of both said clutch means, then eirect selective shift movement of said large torque capacity clutch, and then effect ria-engagement of both said clutch' means.

19. In a transmission, a plurality of gears providing differentspeed drive ratios, clutch means of relatively large friction torque capacity selectively shiftable relative to said gears for fricj tional engagement with a selected gear,la secondl and shift means including a cam and hydraulic pressure -control means, said shiftmeans being movable from one drive ratio position to another to rst cut of! hydraulic pressure from said clutch,

then shift said clutch to another gear, and then restore the hydraulic pressure to said clutch.

21. In a transmission, a plurality of gears affording different speed drive ratios, a clutch selectively shiftable relative to said gears and operable into engagement therewith upon the application of fluid pressure to said clutch, means .connected to said clutch and operative for shifting said clutch, and passage means for the clutchoperating fluid pressure extending through said clutch shifting means.

22. A composite clutch unit comprising a housing member, clutch means disposed within said ho'using member, and at least a portion of said housing member being radially expansible to provide a clutching surface in series with the clutch means within said housing.

viding diilerent speed drive ratios. clutch means of relatively large friction torque capacity selectively shiftable relative to said gears for frictional engagement with.aseiected gear, second clutch means of relatively large slippage capacity serially connected in said transmission, and common mans for loading both said clutch means.

25. In a multi-speed transmission, a plurality of co-axialgears disposed in side-by-side relation, a clutch axially slidable relative to said gears and having an annular portion radially strainable into frictional 4engagement with a selected gear,

. 'and meansto eiect applicationvof a hydraulic pressurewithin said clutch for radially straining said annular portion.

26;" In 4.a multi-speed transmission, a plurality of izo-axial gears disposed in side-by-side relation,

.' a clutchaxially shiftable relative to said gears and including an annular clutch portion, and

clutch means of relatively large slippage capacity serially connected in said transmission. and inertia means adapted to control the loading of application of hydraulic pressure to said clutch,

means for radially straining said annular portion into frictional engagement with a. selected gear, said means comprising a conical member co-axial with said annular portion, roller means between said conical member and annular portion adapted to radially strain said annular portion upon relative axial movement of said conical member and annular portion, and means for applying hyd raulic pressure between said clutch and member to en'ect said relative movement.

' ROLAND CHILTON. 

